February 18, 2020
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Regular thyroid testing recommended regardless of diabetes type

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Paul Chubb

Thyroid dysfunction is common among people with diabetes regardless of type, suggesting that biochemical thyroid screening should be a part of routine management for those with type 1 and type 2, according to an analysis of a community-based study published in Clinical Endocrinology.

The American Diabetes Association recommends universal screening for thyroid dysfunction in type 1 diabetes, Paul Chubb, PhD, FFSc (RCPA), an adjunct associate professor at University of Western Australia Medical School, and colleagues wrote in the study background. The ADA previously recommended thyroid screening for women aged at least 50 years with type 2 diabetes; however, the current ADA guideline and that of the U.K. National Institute for Health and Care Excellence do not recommend thyroid function monitoring in type 2 diabetes.

“We examined the prevalence and incidence of thyroid disease in a well-characterized community-based sample of people with diabetes in the Fremantle Diabetes Study Phase II,” Chubbs told Healio. “About 3% acquired thyroid disease during nearly 7 years of follow-up, highlighting the need for periodical thyroid function testing.”

In an observational study, Chubb and colleagues analyzed data from 1,617 adults participating in the Fremantle Diabetes Study Phase II, including 130 (8%) with type 1 diabetes, 1,408 (87.1%) with type 2 diabetes and 79 (4.9%) with latent autoimmune diabetes in adults (LADA). Researchers assessed thyroid-stimulating hormone and free thyroxine at baseline between 2008 and 2011 and in those attending follow-up at 4 years.

Thyroid ultrasound female 2 2019.  
Thyroid dysfunction is common among people with diabetes regardless of type, suggesting that biochemical thyroid screening should be a part of routine management for those with type 1 and type 2.
Source: Adobe Stock

Within the cohort, 189 adults (11.7%) had known thyroid disease, determined from self-reported thyroid medication use at baseline or hospitalization data.

Among the remaining 1,428 participants, 73 (5.1%) had biochemical evidence of subclinical hypothyroidism, 15 (1.1%) had overt hypothyroidism, two participants (0.1%) had subclinical hyperthyroidism and three participants (0.2%) had overt hyperthyroidism, for an overall baseline prevalence of thyroid disease of 17.4%.

During 5,694 patient-years of follow-up, 25 (3%) of the 844 participants with a normal baseline TSH and follow-up data developed known thyroid disease. Of the remaining 819, 3.4% developed subclinical hypothyroidism, 0.2% developed overt hypothyroidism and 0.5% developed subclinical hyperthyroidism.

In analyses stratified by diabetes type, researchers observed no between-group differences in the prevalence or incidence of thyroid dysfunction.

“The prevalence of thyroid disease is about the same regardless of the type of diabetes, mainly because the average age of people with type 2 diabetes was higher than that of those with type 1 diabetes,” Chubb said. “Thus, in contrast to recent guidelines for management of diabetes, our results suggest that regular thyroid function testing is probably indicated for all people with diabetes, not just those with type 1. However, we also found that mild abnormalities of thyroid function test results were frequently transient, so that appropriate repeat testing and careful interpretation of the results is needed if overdiagnosis is to be avoided.”

Chubb said more research is needed regarding any association between thyroid disease among people with diabetes and comorbidities and mortality.

“While large, general population studies do not show significant effects of mild thyroid dysfunction on mortality, it is possible that it may contribute to, or interact with, the comorbidities of diabetes such as lipid metabolism and glucose regulation, and these aspects have not been well studied,” Chubb said – by Regina Schaffer

For more information:

Paul Chubb, PhD, FFSc (RCPA), can be reached at University of Western Australia Medical School, Fiona Stanley Hospital, 102-118 Murdoch Drive, Murdoch, WA 6150; email: paul.chubb@health.wa.gov.au.

Disclosures: The authors report no relevant financial disclosures.